Epigenetic modifications refer to changes in gene expression that do not involve alterations to the underlying DNA sequence. These modifications can be influenced by environmental factors and experiences, and they play a role in regulating when, where, and to what extent genes are turned on or off. Examples of epigenetic modifications include DNA methylation, histone modification, and changes in gene expression caused by small RNA molecules. These modifications can have long-lasting effects on an organism's health and behavior, and they may be passed down through generations.